Reaction: (1) oleoyl-CoA + 2 ferrocytochrome b5 + O2 + 2 H+ = linoleoyl-CoA + 2 ferricytochrome b5 + 2 H2O
(2) palmitoleoyl-CoA + 2 ferrocytochrome b5 + O2 + 2 H+ = (9Z,12Z)-hexadeca-9,12-dienoyl-CoA + 2 ferricytochrome b5 + 2 H2O
Glossary: oleoyl-CoA = cis-octadec-9-enoyl-CoA = (9Z)-octadec-9-enoyl-CoA = 18:1 cis-9 = 18:1(n-9)
linoleoyl-CoA = cis,cis-octadeca-9,12-dienoyl-CoA = (9Z,12Z)-octadeca-9,12-dienoyl-CoA = 18:2(n-6)
palmitoleoyl-CoA = (9Z)-hexadec-9-enoyl-CoA
Other name(s): oleoyl-CoA 12-desaturase; Δ12 fatty acid desaturase; Δ12(ω6)-desaturase; oleoyl-CoA Δ12 desaturase; Δ12 desaturase; Δ12-desaturase; Δ12-fatty-acid desaturase; acyl-CoA,hydrogen donor:oxygen Δ12-oxidoreductase
Systematic name: acyl-CoA,ferrocytochrome b5:oxygen oxidoreductase (12,13 cis-dehydrogenating)
Comments: This microsomal enzyme introduces a cis double bond at position 12 of fatty-acyl-CoAs that contain a cis double bond at position 9. When acting on 19:1Δ10 fatty acyl-CoA the enzyme from the pathogenic protozoan Trypanosoma brucei introduces the new double bond at position 13, indicating that the new double bond is introduced three carbons from the existing cis double bond, towards the methyl-end of the fatty acid. Requires cytochrome b5 as the electron donor [4].
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:
References:
1. Borgeson, C.E., de Renobales, M. and Blomquist, G.J. Characterization of the Δ12 desaturase in the American cockroach, Periplaneta americana: the nature of the substrate. Biochim. Biophys. Acta 1047 (1990) 135-140. [PMID: 2248971]
2. Lomascolo, A., Dubreucq, E. and Galzy, P. Study of the Δ12-desaturase system of Lipomyces starkeyi. Lipids 31 (1996) 253-259. [PMID: 8900454]
3. Tocher, D.R., Leaver, M.J. and Hodgson, P.A. Recent advances in the biochemistry and molecular biology of fatty acyl desaturases. Prog. Lipid Res. 37 (1998) 73-117. [PMID: 9829122]
4. Petrini, G.A., Altabe, S.G. and Uttaro, A.D. Trypanosoma brucei oleate desaturase may use a cytochrome b5-like domain in another desaturase as an electron donor. Eur. J. Biochem. 271 (2004) 1079-1086. [PMID: 15009186]